Daughters of women exposed to a common chemical found in some plastics while they were pregnant are more likely to have unusually aggressive and hyperactive behaviors as 2-year-olds, according to a new study by researchers at Simon Fraser University, the University of North Carolina at Chapel Hill and Cincinnati Children’s Hospital.

Joe Braun

Joe Braun, doctoral student in epidemiology at the UNC Gillings School of Global Public Health, is the study’s lead author.

The study, published Oct. 6, 2009 in the journal Environmental Health Perspectives, is the first to examine whether there is a link between prenatal bisphenol A (BPA) exposure and behavior problems in children. Results suggest that if a woman is exposed to BPA early in her pregnancy, development of the baby’s nervous system might be adversely affected.

BPA is commonly used in the production of polycarbonate plastics and epoxy resins that can be found, for example, in some types of plastic bottles, canned food linings, water supply pipes and medical tubing. About 93 percent of people in the United States have detectible levels of BPA in their urine, according to the Centers for Disease Control and Prevention.

Researchers found that daughters of women who had higher concentrations of BPA in their urine samples during pregnancy were more likely to have aggressive and hyperactive behaviors than children of women with lower BPA levels, especially if higher exposure was seen earlier in pregnancy.

“In other words, girls whose mothers had higher BPA exposure were more likely to act like boys than girls whose mothers had lower BPA levels, especially if the exposure was seen earlier in pregnancy,” said lead author Braun. “Boys’ behavior did not seem to be affected, although there was some evidence of increased internalizing scores among BPA-exposed boys.”

Researchers do not know why girls seem to be affected by the exposure more or differently than boys.

BPA has been used in products for decades, and concerns about its safety have been growing in recent years, Braun said. Previous studies in mice have shown that the offspring of mothers with high BPA exposure during pregnancy were more aggressive than offspring not exposed to high prenatal levels of BPA.

“We wanted to know if there was a risk in humans for neurodevelopment problems,” he said. “Study results indicate that exposure to BPA early in the pregnancy seems to be the most critical issue. The most damaging exposure might happen before a woman even knows she’s pregnant.”

Braun worked with researchers at the Cincinnati Children’s Hospital Medical Center, the University of Cincinnati, the Centers for Disease Control and Prevention, and Simon Fraser University in Vancouver, British Columbia.

For the study, urine samples were taken from 249 pregnant women in Cincinnati, Ohio, at 16 weeks and 26 weeks of pregnancy, and again at birth. BPA concentrations in the samples were measured. Then, when the children were 2 years old, behavior problems were assessed, using the Behavioral Assessment System for Children-2 (BASC-2).

“Many government agencies and consumers in the U.S., Canada and around the world have expressed concerns about BPA exposure, especially in children,” said Dr. Bruce Lanphear, professor of children’s environmental health in the Faculty of Health Sciences at Simon Fraser University and the study’s senior author. “Canada has banned BPA in baby bottles and other baby products, but that might not be sufficient to protect children. Although this is the first study of its kind, it suggests that we may also need to reduce exposures during pregnancy.”

The study was funded in part by the National Institute of Environmental Health Sciences and the U.S. Environmental Protection Agency.